Sankrantis in 2020

The moment the Sun passes from one rasi into the next is a sankranti, named for the sign it enters, as in Makara Sankranti. There are twelve a year, and each begins a solar month. The solar calendars of Bengal, Odisha, Tamil Nadu and Kerala count their months from them.

Makara and Karka are the ayana sankrantis (the Sun turns north or south); Mesha and Tula the vishuva (equinoctial) ones; Mithuna, Kanya, Dhanu and Meena are shadashiti-mukha; Vrishabha, Simha, Vrishchika and Kumbha are vishnupadi. Each kind has its own punya kaal.

The Nirnaya Sindhu quotes Hemadri’s verse: 20 ghatis before a Karka sankranti, 20 after a Makara one, 10 on either side of Mesha and Tula, 60 after a shadashiti-mukha and 16 on either side of a vishnupadi are punya (1 ghati = 24 minutes). Bathing and giving are done by day, so the daylight part of that window is given here.

The astronomical winter solstice (the shortest day) falls about 21 December. Makar Sankranti is counted in sidereal signs (against the stars), so it comes about 24 days later. That gap is the ayanamsa, and it grows by about a day every 72 years.

The Sun’s apparent position from NASA JPL’s DE421 ephemeris, less the Lahiri ayanamsa; the sankranti is the instant it crosses a multiple of 30°. Sunrise and sunset are for the chosen city.